Device for variable adjustment of the timing of gas exchange valves of an internal combustion engine

ABSTRACT

A device for the variable adjustment of the timing of gas exchange valves of an internal combustion engine, which has a hydraulic phase shifting device, a camshaft and a pressurizing distributor. The phase shift device can come into drive linkage with a crankshaft and is rigidly connected to the camshaft. A phase position of the camshaft relative to the crankshaft can be variably adjusted by the phase shift device. The interior of the camshaft has a cavity that communicates with one or more camshaft bearings which are separate from a rotating pressurizing means conveyor. The pressurizing distributor is disposed in a receiving area of the camshaft. The camshaft has an opening in the area of the pressurizing means distributor which with the interior of the camshaft and the rotating pressurizing conveyor. A pressurizing path is designed inside the camshaft which communicates with the opening and the hydraulic phase shift device.

AREA OF THE INVENTION

The invention relates to a device for the variable adjustment of the timing of gas exchange valves of an internal combustion engine having a hydraulic phase shifting device, a camshaft, and a pressurizing means distributor, the phase shifting device being able to be brought into a drive connection with a crankshaft and being connected in a rotationally-fixed manner to the camshaft, a phase location of the camshaft relative to the crankshaft being variably adjustable using the phase shifting device, the interior of the camshaft having a cavity, which communicates with one or more camshaft bearings, which are formed separately from a rotating pressurizing means conveyor, the pressurizing means distributor being situated in a receptacle area of the camshaft, the camshaft having an opening in the area of the pressurizing means distributor, which communicates on one side with the interior of the camshaft and on the other side with the rotating pressurizing means conveyor, a pressurizing means path being formed inside the camshaft, which communicates on one side with the opening and on the other side with the hydraulic phase shifting device.

BACKGROUND OF THE INVENTION

In modern internal combustion engines, devices for the variable adjustment of the timing of gas exchange valves are used in order to make the phase relation between crankshaft and camshaft variable within a defined angle range, between a maximum advance position and a maximum retard position. The device typically comprises a camshaft, a hydraulic phase shifting device, by means of which a phase relation between the crankshaft and the camshaft can be intentionally changed by supplying or removing pressurizing means, and a pressurizing means distributor, by means of which pressurizing means can be supplied to the phase shifting device or removed therefrom. For this purpose, the phase shifting device is integrated in a drivetrain, via which torque is transmitted from the crankshaft to the camshaft. This drivetrain can be designed as a belt drive, chain drive, or gearwheel drive, for example.

Such a device is known, for example, from DE 10 2005 052 481 A1. The device comprises a phase shifting device, a central screw, and a camshaft, which is mounted using multiple camshaft bearings in the cylinder head of the internal combustion engine. The phase shifting device has an output element, which is situated so it is rotatable to a drive element. The drive element has a drive connection to the crankshaft. The device is delimited in the axial direction by a lateral cover on each side. The output element, the drive element, and the two lateral covers delimit multiple pressure spaces, each of the pressure spaces being divided using a wing into two pressure chambers, which act against one another. By supplying pressurizing means to or removing pressurizing means from the pressure chambers, the wings are displaced within the pressure spaces, whereby targeted pivoting of the output element to the drive element and therefore of the camshaft to the crankshaft can be caused.

The phase shifting device is connected in a rotationally-fixed manner to the camshaft using the central screw. The central screw penetrates through a central opening of the output element and is supported on the output element on its lateral surface facing away from the camshaft. A control valve, to which pressurizing means is supplied via a camshaft bearing, is situated inside the central screw in the area of the central opening. Using the control valve, the pressurizing means streams to or from the pressure chambers and thus the phase relation between crankshaft and camshaft are controlled.

This embodiment has the disadvantage that complex lubricant supply lines must he implemented within the cylinder head for each camshaft bearing in order to supply lubricant to the camshaft bearings. This significantly increases the complexity and production costs of the cylinder head.

OBJECT OF THE INVENTION

The invention is based on the object of providing a device for the variable adjustment of the timing of gas exchange valves of an internal combustion engine, the lubricant supply of the camshaft bearings being simplified.

The object is achieved as claimed in the invention in that a second pressurizing means duct is provided, which communicates on one side with the opening and on the other side with the cavity, the second pressurizing means duct being at least partially formed by the pressurizing means distributor.

In the process it can be ensured that the pressurizing means distributor is provided with a threaded section, by means of which the phase shifting device is fastenable on the camshaft.

In a refinement of the invention, the pressurizing means distributor has a control valve, by means of which the phase shifting device can be supplied with pressurizing means.

The pressurizing means distributor can penetrate a central opening of the phase shifting device.

The second pressurizing means duct can be formed inside the pressurizing means distributor, for example. Alternatively, the second pressurizing means duct can be formed on an interface between the cavity and the pressurizing means distributor. For example, the second pressurizing means duct can be formed as a longitudinal groove on an outer lateral surface of the pressurizing means distributor or on an inner lateral surface of the camshaft in the area of the pressurizing means distributor.

The rotating pressurizing means conveyor can be designed as a camshaft bearing, for example.

Furthermore, the pressurizing means path can be at least partially formed by the pressurizing means distributor.

The device has at least one hydraulic phase shifting device, one camshaft, and one pressurizing means distributor. The phase shifting device comprises at least one drive element and one output element. In the installed state of the device, the drive element has a drive connection to the crankshaft via a traction drive, for example, a belt or chain drive, or a gearwheel drive. The output element is situated so it is pivotable relative to the drive element in an angle range and is fastened in a rotationally-fixed manner on the camshaft.

At least one pressure chamber is provided inside the device, by whose pressure impingement the output element can be pivoted relative to the drive element and thus the camshaft can be pivoted relative to the crankshaft. One or more pairs of pressure chambers which act against one another are advantageously provided.

The camshaft is designed as a hollow shaft having a cavity. This can be implemented, for example, in that the camshaft comprises a tube, one end of which is closed and is fastened on the cam in a friction-locked, formfitting, or materially bonded manner. However, solidly implemented camshafts are also conceivable, which have an axial duct in the form of a drilled pocket hole, which opens into a receptacle in which the pressurizing means distributor is situated.

The camshaft is mounted in multiple camshaft bearings, the cavity communicating with at least one of the camshaft bearings via radial openings in the camshaft. The pressurizing means distributor is received in a receptacle of the camshaft, this receptacle communicating with the cavity. The receptacle can be part of the cavity, for example.

The camshaft has an opening in the area of the receptacle, in which the pressurizing means distributor is situated. A rotating pressurizing means conveyor is situated in this area. It can completely encompass the camshaft in the peripheral direction, for example. The rotating pressurizing means conveyor can be designed as a camshaft bearing or as a separate component. Pressurizing means is supplied permanently or at intervals to the interior of the camshaft during the operation of the internal combustion engine via the rotating pressurizing means conveyor and the opening. Inside the camshaft, the pressurizing means distributor separates a pressurizing means path, which is provided for the supply of the phase shifting device from a second pressurizing means duct, which opens into the cavity of the camshaft and via which the camshaft hearing, which is separate from the rotating pressurizing means conveyor, is supplied with lubricant. The pressurizing means distributor closes the cavity pressure-tight to the outside, except for the second pressurizing means duct. A filter element can additionally be integrated in the second pressurizing means duct, which keeps foreign bodies located in the lubricant or pressurizing means away from the camshaft bearings and thus reduces the wear of the bearing points. Since all camshaft bearings are supplied with lubricant/pressurizing means via the second pressurizing means duct, only a single filter element is required in this embodiment. The rotating pressurizing means conveyor can fulfill still further functions in addition to guiding the lubricant/pressurizing means streams. For example, a threaded section can be formed thereon, by means of which the phase shifting device, for example, the output element, can be connected in a rotationally-fixed manner to the camshaft. It is also conceivable that the pressurizing means distributor has a control valve, via which the pressurizing means streams to and from the pressure chambers of the phase shifting device can be controlled. Multiple functionalities can thus be represented by one component, whereby the number of the components and therefore the installation effort, the overall space requirement of the device, and the costs thereof sink.

The second pressurizing means duct, which communicates on one side with the opening and therefore with the rotating pressurizing means conveyor and on the other side with the cavity of the camshaft, is at least partially formed by the pressurizing means distributor. For example, a pressurizing means distributor is conceivable in whose interior a drilled hole is provided, which branches off from the pressurizing means path, which supplies the phase shifting device with pressurizing means. In this case, the second pressurizing means duct is solely formed by the pressurizing means distributor. Embodiments are also conceivable in which the second pressurizing means duct is formed on an interface between the pressurizing means distributor and the camshaft, for example, an inner lateral surface of the camshaft and an outer lateral surface of the pressurizing means distributor. This can be formed by a longitudinal groove, for example, which is formed on the outer lateral surface of the pressurizing means distributor or the inner lateral surface of the camshaft.

A minimal passage surface of the second pressurizing means duct is advantageously designed as smaller than a minimal passage surface of the pressurizing means path between the opening and the phase shifting device. For example, the second pressurizing means duct can have a throttle point. The throttle point can be formed using a separate component, for example, which is situated in the second pressurizing means duct. The pressurizing means stream to the camshaft bearings can thus be reduced to the required amount, while in contrast the pressurizing means can be supplied unthrottled to the phase shifting device. The high pressurizing means stream to the phase shifting device results in a high response behavior and high adjustment speeds. The required volume stream is simultaneously limited in that a smaller volume stream is supplied to the camshaft bearings. This relieves the pressurizing means pump of the internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the invention result from the following description and the drawings, in which exemplary embodiments are shown in simplified form. In the figures:

FIG. 1 very schematically shows an internal combustion engine,

FIG. 2 shows a longitudinal section through a first embodiment as claimed in the invention of a device for varying the timing of gas exchange valves of an internal combustion engine,

FIG. 3 shows a cross-section through the phase shifting device from FIG. 2 along line III-III,

FIG. 4 shows a longitudinal section through a second embodiment as claimed in the invention of a device similar to FIG. 2, only the camshaft and the pressurizing means distributor being shown,

FIG. 5 shows a longitudinal section through a third embodiment as claimed in the invention of a device similar to FIG. 2, only the camshaft and the pressurizing means distributor being shown.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sketch of an internal combustion engine 1, a piston 3 seated on a crankshaft 2 being indicated in a cylinder 4. The crankshaft 2 is connected in the illustrated embodiment via a traction drive 5 in each case to an inlet camshaft 6 or outlet camshaft 7, a first and a second device 11 being able to ensure a relative rotation between crankshaft 2 and the camshafts 6, 7. Cams 8 of the camshafts 6, 7 actuate one or more inlet gas exchange valves 9 or one or more outlet gas exchange valves 10. Only one of the camshafts 6, 7 can also be equipped with a device 11, or only one camshaft 6, 7 can be provided, which is provided with a device 11.

FIGS. 2 and 3 show a first embodiment of a device 11 as claimed in the invention in longitudinal section and cross-section, respectively. The device 11 has a phase shifting device 12, a camshaft 6, 7, and a pressurizing means distributor 13.

The phase shifting device 12 comprises a drive element 14 and an output element 16. The drive element 14 has a housing 15 and two lateral covers 17, 18, which are situated on the axial lateral surfaces of the housing 15. The output element 16 is designed in the form of an impeller wheel and has an essentially cylindrical hub element 19, from whose external cylindrical lateral surface five wings 20 extend outward in the radial direction in the embodiment shown. Starting from an outer peripheral wall 21 of the housing 15, five projections 22 extend radially inward. In the illustrated embodiment, the projections 22 and the wings 20 are integrally formed with the peripheral wall 21 or the huh element 19, respectively. The drive element 14 is situated so it is rotatable relative to the output element 16 using radial inner peripheral walls of the projections 22.

A chain wheel 23, via which torque can be transmitted from the crankshaft 2 to the drive element 14 using a chain drive (not shown), is implemented on an outer lateral surface of the first lateral covers 17. The output element 16 is connected in a rotationally-fixed manner to the camshafts 6, 7. For this purpose, in the illustrated embodiment, the pressurizing means distributor 13 is provided with a threaded section 24, which engages in a threaded section 25 of the camshafts 6, 7. The pressurizing means distributor 13 penetrates a central opening 16 a of the output element 16. A shoulder of the pressurizing means distributor 13 presses against the lateral surface of the output element 16 facing away from the camshaft 6, 7.

Each one of the lateral covers 17, 18 is situated on one of the axial lateral surfaces of the housing 15 and fixed in a rotationally-fixed manner thereon. For this purpose, an axial opening 26 is provided in each projection 22. Furthermore, five openings are provided in each of the lateral covers 17, 18, which are situated in such a manner that they align with the axial openings 26. One screw 27 penetrates an opening of the second lateral cover 18, an axial opening 26, and an opening of the first lateral covers 17 in each case. A threaded section of the screw 27 engages in a threaded section which is formed in the opening of the first lateral cover 17.

A pressure space 28 is formed inside the device 11 between each two adjacent projections 22 in the peripheral direction. Each of the pressure spaces 28 is delimited in the peripheral direction by opposing, essentially radial delimitation walls 29 of adjacent projections 22, in the axial direction by the lateral covers 17, 18, radially inward by the hub element 19, and radially outward by the peripheral wall 21. A wing 20 protrudes into each of the pressure spaces 28, the wings 20 being designed in such a manner that they press against both the lateral covers 17, 18 and also the peripheral wall 21. Each wing 20 therefore divides the respective pressure space 28 into two pressure chambers 30, 31, which act against one another.

The output element 16 is situated so it is rotatable in a defined angle range to the drive element 14. The angle range is delimited in one rotational direction of the output element 16 in that the wings 20 come to rest on a corresponding delimitation wall 29 (advance stop 32) of the pressure spaces 28. The angle range is similarly delimited in the other rotational direction in that the wings 20 come to rest on the other delimitation walls 29 of the pressure spaces 28, which are used as the retard stop 33.

By pressure impingement of one group of pressure chambers 30, 31 and pressure relief of the other group, the phase location of the drive element 14 to the output element 16 (and thus the phase location of the camshaft 6, 7 to the crankshaft 2) can be varied. The phase location can be kept constant by pressure impingement of both groups of pressure chambers 30, 31.

The pressurizing means distributor 13 is provided with a control valve 34 to supply the phase shifting device 12 with pressurizing means. The control valve 34 comprises an essentially hollow-cylindrical valve housing 35 and a control piston 36, which is situated so it is axially displaceable inside the valve housing 35. The valve housing 35 is provided with an inflow connection P, an outflow connection T, and two working connections A, B.

The pressurizing means distributor 13 penetrates the central opening 16 a of the output element 16, the section thereof facing toward the camshaft being situated in a receptacle 37 of the hollow camshaft 6, 7. The camshaft 6, 7 has multiple openings 38 in the area of the receptacle 37, which communicate on one side with a rotating pressurizing means conveyor 39, which at least partially encompasses the camshaft 6, 7, and on the other side with the interior of the camshaft 6, 7. In the illustrated embodiment, the rotating pressurizing means conveyor 39 is simultaneously designed as a camshaft bearing 50. Via the rotating pressurizing means conveyor 39 and the openings 38, pressurizing means is supplied during the operation of the internal combustion engine 1 from the lubricant circuit thereof to the interior of the camshaft 6, 7. Embodiments are also conceivable in which the rotating pressurizing means conveyor 39 is implemented separately from the camshaft bearings 50 and exclusively allows the pressurizing means transfer between components fixed on the cylinder head and the camshaft 6, 7.

The pressurizing means distributor 13 is designed and situated in such a manner that a pressurizing means path 40 is formed, which communicates on one side with openings 38 and on the other side with the inflow connection P. In the illustrated embodiment, the pressurizing means path 40 comprises a first pressurizing means duct 41 between the outer lateral surface of the pressurizing means distributor 13 and the inner lateral surface of the camshaft 6, 7, which communicates with radial openings 42, which in turn communicate with the interior of the pressurizing means distributor 13. From there, the pressurizing means reaches the inflow connection P via a check valve 43 and an axial duct 44.

Depending on the axial position of the control piston 36 to the valve housing 35, the pressurizing means reaches either the first or second working connection A, B and from there, via radial pressurizing means lines 45, 46, the first or second pressure chambers 30, 31. The pressurizing means is simultaneously returned from the other pressure chambers 30, 31 via the pressurizing means lines 45, 46 to the control valve 34 and expelled via the outflow connection T. The axial position of the control piston 36 relative to the valve housing 35 is intentionally adjustable using an electromagnetic actuator 47.

A second pressurizing means duct 48 is provided in the interior of the pressurizing means distributor 13, which communicates on one side via the radial openings 42 and the first pressurizing means duct 41 with openings 38 and on the other side with a cavity 49 of the hollow camshaft 6, 7. The second pressurizing means duct 48 is designed as an axial drilled hole which penetrates the threaded section 24 in the embodiments shown in FIGS. 2 and 4. The cavity 49 extends, as shown in FIG. 4, over the entire length of the camshaft 6, 7, its side facing away from the phase shifting device 12 being designed as closed and being delimited in the other direction by the pressurizing means distributor 13. The pressurizing means distributor 13 seals the cavity 49 to the outside, except for the second pressurizing means duct 48. The camshaft 6, 7 is mounted using one or more camshaft bearings 50 so it is rotatable in the cylinder head of the internal combustion engine 1. At least one, advantageously multiple radial openings 51 are provided in the area of each of these camshaft bearings 50, which communicate on one side with the cavity 49 and on the other side with the hearing surface of the camshaft hearing 50. Lubricant is thus supplied to the camshaft bearings 50 via the rotating pressurizing means conveyor 39, the openings 38, the first pressurizing means duct 41, the radial openings 42, the second pressurizing means duct 48, the cavity 49, and the radial openings 51. Furthermore, a filter element 54 is provided, which frees the pressurizing means/lubricant stream to the camshaft bearings and the phase shifting device 12 from contaminants. In the illustrated embodiment, the filter element 54 is designed as a ring filter.

In order to ensure a high response speed and a high adjustment speed of the phase shifting device 12, it is necessary to allow a high volume stream to the phase shifting device 12. It is simultaneously advantageous to limit the volume stream to the camshaft bearings 50 to a minimum which ensures their functional capability. The required volume stream which must be provided via the rotating pressurizing means conveyor 39 can thus be reduced, high response and adjustment speeds of the phase shifting device 12 being ensured simultaneously. For this purpose, a throttle 52 is provided inside the second pressurizing means duct 48, which delimits the pressurizing means stream from the rotating pressurizing means conveyor 39 to the bearing surfaces of the camshaft bearings 50 without obstructing the pressurizing means stream to the phase shifting device 12. In the embodiment shown in FIG. 4, the throttle 52 is formed separately from the pressurizing means distributor 13 and is fastened fixed in place in the second pressurizing means duct 48, for example, by a formfitting, materially-bonded, or friction-locked connection. Embodiments are also conceivable in which the diameter of the second pressurizing means duct 48 is designed in such a manner that the throttle function is induced thereby (FIG. 2) or in which the throttle 52 is formed on the pressurizing means distributor 13. In all cases, the minimal passage surface of the second pressurizing means duct 48 is designed as smaller than the minimal passage surface between the rotating pressurizing means conveyor 39 and the pressure chambers 30, 31.

FIG. 5 shows a further embodiment as claimed in the invention of the device 11, which is designed essentially identically to the first two embodiments. In contrast to the first two embodiments, the second pressurizing means duct 48 is formed on the interface between the inner lateral surface of the camshaft 6, 7 and the outer lateral surface of the pressurizing means distributor 13. For this purpose, a longitudinal groove 53 is provided, which communicates on one side with the cavity 49 and on the other side with the first pressurizing means duct 41. The longitudinal groove 53 can be formed, for example, on the inner lateral surface of the camshaft 6, 7 or the outer lateral surface of the pressurizing means distributor 13. In each case, the second pressurizing means duct 48 is thus partially delimited by the pressurizing means distributor 13. In this embodiment, the pressurizing means stream to the camshaft bearings 50 is also throttled. This can be achieved, for example, as shown in FIG. 5, via a suitable layout of the cross-section of the longitudinal groove 53. The longitudinal groove 53 can have a constant small cross-section or a local throttle point.

Using the invention, one or more camshaft bearings 50 which are separate from the rotating pressurizing means conveyor 39 can be supplied with lubricant. The structures which are otherwise typical in the cylinder head for the lubricant supply of each individual camshaft bearing 50 can thus be dispensed with, whereby the complexity and the costs of the cylinder head are reduced. Through the pressurizing means supply of all camshaft bearings 50 via the cavity 49 of the camshaft 6, 7, only a pressurizing means supply to the camshaft 6, 7 is necessary, via which the phase shifting device 12 is supplied simultaneously. The formation of the second pressurizing means duct 48 by the pressurizing means distributor 13 significantly reduces the costs and the complexity of the device 11. The supply of the phase shifting device 12 and the camshaft bearings 50 can thus be implemented using a single component, whereby the installation expenditure sinks significantly.

LIST OF REFERENCE NUMERALS

1 Internal combustion engine

2 Crankshaft 3 Piston 4 Cylinder

5 Traction drive 6 Inlet camshaft 7 Outlet camshaft

8 Cams

9 Inlet gas exchange valve 10 Outlet gas exchange valve

11 Device

12 Phase shifting device 13 Pressurizing means distributor 14 Drive element

15 Housing

16 Output element 16 a Central opening 17 Lateral cover 18 Lateral cover

19 Hub 20 Wing

21 Peripheral wall

22 Projection

23 Chain wheel 24 Threaded section 25 Threaded section 26 Axial opening

27 Screw

28 Pressure space 29 Delimitation wall 30 First pressure chamber 31 Second pressure chamber 32 Advance stop 33 Retard stop 34 Control valve 35 Valve housing 36 Control piston

37 Receptacle 38 Openings

39 Rotating pressurizing means conveyor 40 Pressurizing means path 41 First pressurizing means duct 42 Radial openings 43 Check valve 44 Axial duct 45 First pressurizing means line 46 Second pressurizing means line

47 Actuator

48 Second pressurizing means duct

49 Cavity

50 Camshaft bearing 51 Radial opening

52 Throttle

53 Longitudinal groove 54 Filter element A First working connection B Second working connection P Inflow connection T Outflow connection 

1-14. (canceled)
 15. A device for variable adjustment of timing of gas exchange valves of an internal combustion engine having a crankshaft, comprising: a hydraulic phase shifting device; a camshaft; a pressurizing medium distributor; and at least one camshaft bearing, the phase shifting device being able to be brought into a drive connection with the crankshaft and being connected in a rotationally-fixed manner to the camshaft, the phase shifting device being operative to variably adjust a phase location of the camshaft, an interior of the camshaft having a receptacle in which the pressurizing medium distributor is arranged, a cavity, which communicates with the camshaft bearing that is formed separately from a rotating pressurizing medium conveyor, an opening in an area of the pressurizing medium distributor, which communicates on one side with the interior of the camshaft and on another side with the rotating pressurizing medium conveyor, and a pressurizing medium path formed inside the camshaft, the path includes a first pressurizing medium duct communicating on one side with the opening and on another side with the hydraulic phase shifting device, and a second pressurizing medium duct at least partially formed by the pressurizing medium distributor and communicating on one side with the opening and on another side with the cavity.
 16. The device as claimed in claim 15, wherein the pressurizing medium distributor has a threaded section and the phase shifting device is fastenable on the camshaft via the threaded section.
 17. The device as claimed in claim 15, wherein the pressurizing medium distributor has a control valve, which can supply the phase shifting device with pressurizing medium.
 18. The device as claimed in claim 15, wherein the phase shifting device has a central opening and the pressurizing medium distributor penetrates the central opening of the phase shifting device.
 19. The device as claimed in claim 15, wherein a minimal passage surface of the second pressurizing medium duct is smaller than a minimal passage surface of the first pressurizing medium duct between the opening and the phase shifting device.
 20. The device as claimed in claim 15, wherein the second pressurizing medium duct is formed inside the pressurizing medium distributor.
 21. The device as claimed in claim 15, wherein the second pressurizing medium duct is formed on an interface between the cavity and the pressurizing medium distributor.
 22. The device as claimed in claim 21, wherein the second pressurizing medium duct is a longitudinal groove on an outer lateral surface of the pressurizing medium distributor.
 23. The device as claimed in claim 21, wherein the second pressurizing medium duct is formed as a longitudinal groove on an inner lateral surface of the camshaft in an area of the pressurizing medium distributor.
 24. The device as claimed in claim 15, wherein the second pressurizing medium duct has a throttle.
 25. The device as claimed in claim 24, wherein the throttle is formed by a separate component arranged in the second pressurizing medium duct.
 26. The device as claimed in claim 15, wherein the rotating pressurizing medium conveyor is a camshaft bearing.
 27. The device as claimed in claim 15, wherein the pressurizing medium path is at least partially formed by the pressurizing medium distributor.
 28. The device as claimed in claim 15, wherein a filter element is arranged in the second pressurizing medium duct. 